The field of the invention is automatic systems for indicating estrus in animals, and more particularly, systems for electronically indicating estrus in dairy cows.
The accurate detection of estrus in animals is a significant factor in reproductive efficiency where artificial insemination is used. When applied to dairy cows, accurate detection of estrus is an important factor in determining the total milk production of the herd. A number of estrus, or heat, detection methods are presently used, but by far the most widely used method is to observe either manually or with a video recorder, the activity of the cow. In a large dairy herd this practice becomes difficult and inefficient.
As reported in the Journal of Dairy Science Vol. 60, No. 2 by Charles A. Kiddy of the U.S. Department of Agriculture, cows are appreciably more active at estrus than at other times during the estrus cycle. This was confirmed by tests run in which pedometers were attached to the hind leg of a number of cows and their activity was monitored over a period of time. In these tests the pedometer counted the number of leg movements and the pedometer was visually read twice a day when the cow was milked. The number of counts at each reading were found to increase by a factor of three or more during estrus.